I've tidied up the code for this site and decided to open source it if anyone is interested. It's running on Rails with Postgres as the database. Posts are stored as markdown using the fantastic EpicEditor markdown editor.
To get started you need to create a user. You can either uncomment out the user resources in the routes file and create the user using the web interface or use the console to generate the user. I recommend using the console at this point since any registered user has access to the admin console.
Steps to create a new user via the console
$ rails console Loading development environment (Rails 3.2.8) irb(main):001:0> User.create(email: 'firstname.lastname@example.org', password: 'mypassword')
Once your user is created you can login via /login and access the admin via /admin.
You can find the blog engine on GitHub at https://github.com/andruu/blog-engine. One big thing I still need to add is testing which should come this week.
If you see any bugs go ahead and send a pull request and if you have any questions you can leave them in the comments below.